Reinforced flexible hose has long been in use in interconnecting various components of automotive air conditioning systems. Typically, these hoses have been provided with fittings which include a ribbed end portion insertable within the end of the flexible hose and a sleeve surrounding the end portion of the hose which is radially compressed or crimped to clamp the hose between the sleeve and end fitting. In order to increase the mechanical strength of the joint as well as to increase the sealing capability thereof, a plurality of annular ribs are often provided on the fitting.
However, recently a composite type reinforced hose material has been developed which offers significant advantages over previous types of reinforced hose constructions in terms of both cost and weight. It should also be noted that this hose construction is also advantageous in that it has a significantly lower permeability to freon gas commonly utilized in automotive air conditioning systems. This composite hose includes an inner liner fabricated from a thermoplastic material which is characterized by its low memory characteristics and low resistance to compression setting. While this hose construction is less costly to manufacture and is lighter in weight, the presence of the liner material renders previous methods of forming fluid-tight seals with fittings relatively unacceptable due to the poor resistance to compression set of the liner material which increases the tendency for leakage to occur. That is to say that when presently known methods are employed to secure end fittings to such composite type hose, the compressive forces created by the crimped sleeve are relieved or reduced because the liner material tends to flow away from areas of maximum compression thereby reducing the sealing effect resulting from the compressive loading exerted thereon. This tendency of such thermoplastic materials to flow increases at elevated temperatures such as may be encountered by such hose assemblies employed in automotive air conditioning due to their location proximate the engine as well as from the heat of compression to which they may be subjected.
The present invention, however, has overcome these problems by providing a separate resilient sealing member positioned between the liner material and male end of the fitting which operates to create a durable and reliable seal therebetween. A sleeve member is provided which clamps the hose and liner against the male end of the fitting, however, because of the presence of the separate sealing member, the loads required to set or crimp the sleeve are substantially reduced thereby facilitating both shop fabrication of the assemblies as well as subsequent repair and/or replacement of the end fittings if required. Thus, the present invention provides an extremely economical and efficient means by which the advantages offered by this new composite hose material may be realized in high pressure fluid environments such as automotive air conditioning systems. Additionally, the present invention is also well suited for use in conjunction with economically securing fittings to the ends of other types of tubes and fluid conduits exhibiting these low memory and low resistance to compression set characteristics.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.